Opening day baseball cards can potentially be worth something, but there are a few key factors that determine their value. The year, players featured, condition of the card, and rarity all play important roles in deciding if an opening day card holds significant monetary worth.

Opening day cards from the late 1980s through the 1990s tend to have the most collector value since baseball card popularity was at its peak during that era. Popular players from that time period like Ken Griffey Jr., Barry Bonds, Cal Ripken Jr., Mark McGwire, and others will command higher prices since they were superstar players collectors love to own.

The specific year is also important. For example, 1989 Topps opening day cards are very desirable since many consider the ’89 Topps set to be one of the most iconic of all-time. Upper deck also released some of the first high-end licensed opening day cards in 1989 that started the boom in hobby boxes and set collections. So a pristine ’89 opening day card could net over $100 depending on the player featured.

On the other hand, opening day issues from the 1970s and early 1980s aren’t as coveted since production runs were larger back then and interest in cardboard wasn’t as high. There are exceptions like a Nolan Ryan or Reggie Jackson rookie from the late 70s could still fetch $50+, but common players from that era are unlikely to sell for more than a few dollars.

Condition is critical too – a flawless, near mint opening day card will demand much higher prices than one that is well-worn or has creases/edges issues. A mint star player from the late 80s/90s boom could sell for several hundred dollars or more, whereas a well-loved copy might only get $10-20 on the open market.

Rarity also comes into play for opening day cards. Parallel issues, autographed versions, special photo variations, and incredibly low print numbering can make even mediocre players exponentially more valuable. For example, Topps released a scarce gold parallel set of their 1989 opening day cards number to only 100 copies. Pulling a Bonds, Ripken, or McGwire in this scarce parallel would make it worth thousands to the right collector.

Autographed opening day cards or ones that feature a specific milestone are also highly sought after rarities. An example would be Cal Ripken Jr’s 2001 opening day card from his final season, which countless collectors hope to find signed to commemorate his legendary consecutive games played streak.

In summary – while all opening day cards carry some nostalgia and collector value, the specific year, featured players, condition, and rarity heavily influence whether a given issue holds significant monetary worth or not. Opening day cards from the late 80s/90s boom in pristine shape have the best chance of retaining value, whereas older, common issues in played condition typically sell for minimal amounts. But the right rare parallel, autograph, or historical milestone can make even average players highly valuable commodities to the right collectors. Savvy collectors know opening day cards are worth evaluating individually based on those key attributes before determining their true collectible or financial worth.